Implantable blood pumps may be used to provide assistance to patients with late stage heart disease. Blood pumps operate by receiving blood from a patient's vascular system and impelling the blood back into the patient's vascular system. By adding momentum and pressure to the patient's blood flow, blood pumps may augment or replace the pumping action of the heart. For example, a blood pump may be configured as ventricular assist device or “VAD.”
A VAD is a device which is used to assist the heart of a mammalian subject such as a human or animal patient. A typical VAD includes a pump which is implanted in the body of the patient. The pump typically has an inlet connected to a source of blood to be circulated, and an outlet connected to an artery. Where a VAD is used to assist the pumping action of the left ventricle, the device draws blood from the left ventricle of the heart and discharges the blood into the aorta. VADs can be used to assist the heart of patients suffering from conditions which impair the pumping ability of the heart. Such assistance can be provided permanently, or while the patient awaits a suitable heart transplant. In other cases, the assistance provided by the VAD allows the heart to heal.
The blood pump may be a miniature rotary impeller pump having an impeller disposed in a pump housing and driven in rotation by a small electric motor which may be closely integrated with the pump. The motor in turn typically is powered by an implantable and/or external power sources such as storage batteries with an arrangement for charging the batteries from an external AC or DC power source. The VAD typically includes a control system which controls operation of the power source so as to drive the impeller at a set rotational speed and thus provide constant pumping action (blood flow).
Many patients who receive a blood pump are also provided with medication. Such medications may improve or regulate operation of the pump, such as a blood thinning medication or a vasodilator that may reduce the risk of thrombus formation in the pump. For such patients it is desirable to be able to ensure that the patient takes the prescribed medication, as well as to ensure that the medication has the desired effect on the patient's health. Furthermore, the fact that the patient is taking medication is yet additional information relating to the patient's condition and operation of the blood pump. It is also desirable to be able to better monitor the patient's health and the blood pump's operation using this additional data input.